Writing the solution of (REF ) as \(u_{H,k,\mu }^{\text{ms}}=u_{H,k,\mu }- {{\mathcal {Q}}_{k,\mu }}(u_{H,k,\mu })\)  with \(u_{H,k,\mu }\in V_H\) ,
we have the following a priori estimate, which was first shown in [1]}.
